This invention relates generally to filter devices and, more particularly, to fuel system filters for small particulate contaminants.
It is well-known that the mechanical cleaning of a filter surface can be accomplished by having a brush or scraper drag along the filter surface where deposits have accumulated. In certain configurations, the brush or scraper is mounted at one end between two walls but with a significant portion of the brush or scraper projecting beyond the walls. Such configurations are shown in U.S. Pat. No. 148,557 (Gillespie et al.); U.S. Pat. No. 556,725 (Farwell); U.S. Pat. No. 740,574 (Kohlmeyer) and U.S. Pat. No. 793,720 (Godbe). In conventional filter systems, the particulate contaminants are driven off the filter surface and are deposited in a hopper or tank along with the fluid being filtered, thus discarding large amounts of the fluid being filtered.
The use of a brush, or high speed cleaning spray, disposed between a pair of walls for cleaning a cylindrical filter is known in the art, as is disclosed in U.S. Pat. No. 5,423,977 (Aoki et al.) and U.S. Pat. No. 5,595,655 (Steiner et al.) and Swiss Patent No.22,863 (Zingg). Another variation employs a backwash that drives the particulate contaminants off of the cylindrical filter, as is disclosed in U.S. Pat. No. 3,338,416 (Barry).
One desirable use for fuel oil filter systems of the present invention is in ships. Prior art ship fuel oil systems use conventional filter cartridges for cleaning the fuel in-line. However, these filter cartridges require frequent replacement which, in turn, requires the fuel flow to be interrupted during replacement. Interruption of the fuel oil flow will shut down the ship""s main engines, thereby rendering the ship incapable of maneuvering. This can be catastrophic where the ship is in tight quarters, e.g., during docking or navigating through narrow passageways, or during storms, or during battle with regard to warships.
Furthermore, there are additional costs of having to store sufficient replacement cartridges onboard, the logistics involved in shipping and disposing the cartridges to and from the ship, and the labor costs involved in replacing the cartridges.
In addition, shipboard fuel oil straining is a specialized straining process. In particular, the fuel oil flow is initially pre-strained for gross particulate contaminants, such that any particulate contaminants remaining in the fuel oil flow are extremely small (e.g.,  less than 100 microns, with a large percentage being less than 25 microns). As a result, where these small particulate contaminants are captured by a downstream strainer (e.g., a wedge wire screen strainer), both on and within the strainer surface, and then later dislodged during the strainer cleaning process, these extremely small particulate contaminants do not fall by gravity toward a drain but remain suspended in the fuel oil and will re-attach to the strainer surface. Therefore, there remains a need for a cleaning device that can dislodge such extremely small particulate contaminants off of the downstream strainer surface, as well as from within the strainer surface, and then ensure that these particulate contaminants flow out through the drain rather than re-attaching to the strainer surface.
Thus, there is a need for an improved system for removing undesired particulate contaminants from a fuel oil flow and without interrupting that fuel oil flow to the engines, while minimizing the amount of fluid removed therewith. It is to just such a system that the present invention is directed.
Accordingly, it is the general object of the instant invention to provide a fuel oil cleaning device that overcomes the problems of the prior art.
It is a further object of this invention to provide a fuel oil cleaning device that permits continuous fuel oil flow even during the cleaning process.
It is a further object of this invention to provide a fuel oil cleaning device that removes small particulate contaminants from a strainer surface, and from within the strainer surface, and ensures that when these small particulate contaminants are dislodged from the strainer during cleaning that they enter a drain rather than re-attaching to the strainer surface.
It is still yet another object of this invention to provide a fuel oil cleaning device that generates a high velocity flow of dislodged particulate contaminants away from the strainer and into a drain.
It is a further object of this invention to provide a fuel oil cleaning device that minimizes the amount of fuel oil that must be discarded during cleaning.
It is still yet a further object of this invention to eliminate the need for frequent replacement of the fuel oil filter.
It is still another object of this invention to minimize the costs associated with frequent fuel oil filter replacements.
It is still yet even another object of this invention to improve the efficiency of particulate removal.
It is still yet another object of this invention to provide a fuel oil filter that can be self-cleaned with the use of a reverse flow of clean fuel oil.
It is even yet another object of this invention to provide a self-cleaning fuel oil filter system that permits the fuel oil filter element to remain stationary during cleaning.
These and other objects of the invention are achieved by providing a fuel oil cleaning system disposed within a fuel oil flow having particulate contaminants therein. As mentioned earlier, the particulate contaminants that need to be removed from the fuel oil flow are extremely small, less than 100 microns, and a large percentage of these less than 25 microns, therefore do not settle out by gravity. The invention of the present application is well-suited to removing these small particulate contaminants from the fuel oil flow and into a drain.
The fuel oil cleaning system comprises: an inlet valve for controlling the fuel oil flow having particulate contaminants therein which forms a contaminated fuel oil flow and wherein the contaminated fuel oil flow flows through a first output port of the inlet valve; a stationary porous member positioned in the contaminated fuel oil flow that passes through the first output port and wherein the contaminated fuel oil flow enters the stationary porous member through a first porous member surface and exits through a second porous member surface towards a second output port; and wherein the contaminated fuel oil flow deposits the particulate contaminants on the first porous member surface to form a clean fuel oil flow that flows toward the second output port; an outlet valve coupled to the second output port for controlling the clean fuel oil flow; a flow control means, operated during a porous member cleaning process, having a flow control means input coupled to a source of clean fuel oil and a flow control means output coupled to the second output port; and wherein the flow control means controls a reverse flow of the clean fuel oil that flows from the second porous member surface through the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of fuel oil; a drain valve coupled to the first output for directing the contaminated reverse flow of fuel oil towards a drain during the cleaning process; and wherein the inlet valve and outlet valve are closed during the cleaning process.
The above invention also includes a method for cleaning a fuel oil flow having particulate contaminants therein. The method comprises the steps of: positioning a stationary porous member in the contaminated fuel oil flow such that the contaminated fuel oil flow enters the stationary porous member through a first porous member surface and exits through a second porous member surface toward an output port, and wherein the contaminated fuel oil flow deposits the particulate contaminants on the first porous member surface; isolating the stationary porous member from the contaminated fuel oil flow during a cleaning process; passing a reverse flow of clean fuel oil from the output port and through the stationary porous member from the second porous surface member surface to the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of fuel oil; opening a drain to receive the contaminated reverse flow of fuel oil; discontinuing the reverse flow of clean fuel oil while closing the drain to complete the cleaning process; and recoupling the stationary porous member to the contaminated fuel oil flow.
Another embodiment of the present invention comprises a fuel oil cleaning system for use with a fuel oil flow having particulate contaminants therein and wherein the cleaning system comprises: an inlet valve for controlling the fuel oil flow having particulate contaminants therein forming a contaminated fuel oil flow and wherein the contaminated fuel oil flows through a first output port of the inlet valve; a stationary porous member positioned in the contaminated fuel oil flow that passes through the first output port and wherein the contaminated fuel oil flow enters the stationary porous member through a first porous member surface and exits through a second porous member surface towards a second output port and wherein the fuel oil flow deposits the particulate contaminants on the first porous member surface to form a clean fuel oil flow that flows towards the second output port; a third output port coupled to a drain through a drain valve; the inlet valve being closed while the drain valve is opened during a cleaning process for generating a reverse flow of the clean fuel oil that flows from the second output port towards the third output port, and wherein the reverse flow of the clean fuel oil flows through the stationary porous member from the second porous member surface through the first porous member surface for dislodging the particulate contaminants from the first porous member surface to form a contaminated reverse flow of fuel oil that flows into the drain; and the drain valve being closed and the inlet valve being opened after the cleaning process is completed.